The invention relates to a device for treating printing plates with a fluid, the printing plates being passed horizontally through a flooded trough composed of a bottom, two lateral boundary walls and containment elements located on each of the inlet and outlet sides.
German Utility Model No. 7,141,280 has disclosed a device for treating printing plates with one or more baths which contain the treatment fluids and through which and over the bottom of which the printing plates are passed by means of conveyor rollers. In particular, the baths are contained by the flat horizontal bottom, containment brushes on the inlet and outlet sides, and lateral boundary walls. Whereas normally a containment brush with only one row of bristles is sufficient for containing the cleansing water bath, the containment brushes for containing the developer bath are provided with rows of bristles, which are located one after the other in the direction in which the plates pass through. In order to minimize the losses of developer fluid, a rubber scraper is also provided on the outlet side, downstream of the containment brush as viewed in the direction of the plates passing through. A first pair of conveyor rollers upstream of the containment brushes and a second pair of conveyor rollers downstream of the containment brushes serve for transporting the printing plates through the bath.
German Offenlegungsschrift No. 2,461,120 describes a device for the treatment of material in the form of sheets, the device having a pre-soaking chamber with an upper and a lower guide plate. The pre-soaking chamber can be open or closed at the sides. For feeding the developer solution into the pre-soaking chamber, two lines are used which are arranged perpendicular to the direction of transport of the printing plates and are connected to the pre-chamber, so that the treatment fluid which is fed in covers the entire width of the introduced material in the form of sheets. The material introduced into the pre-soaking chamber is flooded, between the fluid plates, with developer solution which is fed in through the developer feed lines. This causes turbulence in the developer bath and, since the surfaces of the printing plate come into direct contact with the developer flowing in, the turbulence has disadvantageous effects on the surfaces which are to be developed. In the case of sensitive printing plates, in particular positive printing plates, a cloudy surface development can result. The cloudy surface development is not removed even by subsequent brushing steps with rotating brush rollers. In a modification of this developing device, it is known to spray the developer fluid through developer spray nozzles onto the printing plates being transported through the device. In the case of applying the developer by means of spray tubes or spray nozzles, however, the result is a more or less extensive streaky surface development in the case of particularly sensitive printing plates, in particular positive printing plates.
German Auslegeschrift No. 2,250,278 has disclosed a device for treating printing plates with a fluid, which device comprises a fixed lower part and an upper part which is pivotable about a horizontal axis relative to the former. Two pairs of rollers are provided. The lower roller of each pair of rollers is located in the fixed lower part, whereas the tiltable upper part carries the upper roller of each pair.
German Offenlegungsschrift No. 2,238,414 relates to an apparatus for the simultaneous development of mutually opposite surfaces of planographic printing plates and has a feed device for transporting the planographic printing plate through a developing station which has an upper and a lower plate arranged at a mutual spacing. Between the upper and the lower plates, side walls bounding a developing chamber are arranged at a mutual spacing in such a way that the developing chamber is aligned along the path of movement of the planographic printing plate through the apparatus. At an inlet end of the developing chamber, flexible membranes form a fluid-tight seal and, at the outlet end, the chamber is provided with a throttle which restricts the fluid flow. For filling the developing chamber, the developer fluid is pumped in under uniform pressure from above and from below in such a way that the surfaces of the planographic printing plate come into direct contact with the developer flowing in, so that turbulence is generated on the surfaces of the printing plate which are to be developed. In the case of sensitive positive printing plates, this turbulence can cause cloudy surface development.
German Utility Model No. 7,816,229 relates to a device for treating positive printing plates with a fluid, this device comprising a tank which contains the treatment fluid as the bath and is composed of a bottom, two lateral boundary walls and at least one backing-up element on each of the inlet and outlet sides. The printing plates are transported horizontally through the treatment fluid on the bottom of the tank. The treatment fluid is introduced into the tank via a spray tube and, between the spray tube and the bottom, a baffle is located which prevents direct spraying of the developer fluid onto the surface of the printing plate which is to be developed. The risk of streaky surface development of the printing plate is thus reduced.
In the state of the art, when the treatment fluid is fed into the treatment bath by means of spray tubes, it is in general necessary to incur a certain constructional outlay, such as, for example, the incorporation of baffles between the spray nozzles and the fluid bath, in order to avoid turbulence with its disadvantageous consequences for the development of printing plates. As a result, maintenance and repair work then also become more extensive, since such parts, for example baffles, must be dismantled in order to gain access to the lower transport rollers for the printing plates.